"The idea behind puja is that you are welcoming God over to your place to hang out with you and you are trying to make him feel welcome and happy to be over. It's the same as how you would try to make any important guest feel comfortable when they come over.

Flower petals, rice, or some water can be used to substitute for any items you don't have. In this case you imagine in your inner eye that it is the item it is substituting for. In theory the whole puja can be done with only offering water.

Also it is possible to do the whole puja in your mind only as a meditation."

A 5-Offering Puja

Items Needs:

A hand bell

An achamanam cup with spoon filled with pure water

Incense (air element item)

An oil lamp or candle (fire element item)

A small cup filled with water (water element item)

A tiny plate or little bowl with rice or flowers (earth element item)

A representation of whatever form of the divine you honor

Optional if you wish to do the arati you need some camphor and a plate
or lamp for it to burn on

The ritual:

Invoke Mother Ganges into the achamanam water, say something like:
"Mother Ganges please be in this water" (this makes this holy water
that purifies everything it comes into contact with).

Light all candles/lamps and incense.

-Achamanam (purification ritual for self and space)-

Using your left hand to hold the spoon if possible, sprinkle water
from the achamanam cup onto your left hand and let it fall away.

Still holding spoon do the same with the water onto the right hand and
let it fall away. Let one drop fall upon each of your feet (this
ritual should be done barefoot).

Now put a drop into your right hand and retain it there.

Chant "Aum Kesavaya svaha" and sip this water.

Put a second drop onto your right hand and retain it.

Chant "Aum Narayanaya svaha" and sip this water.

Put a third drop on your right hand and retain it.

Chant "Aum Madhavaya svaha" and sip this water.

Put a drop of water on right hand and let it fall away.

Put another on right hand and hold the water and let it fall on your head or rub it
over your head.

Put a last drop of water on right hand and let it fall away.

Say something like "This pure water purifies everything and drives
away anything unholy" and spoon water drops onto various places and
also put one drop on each of the elemental items and also onto the
bell and anything else on your altar you wish to purify.

-Creating sacred space/time and declaring intent of ritual-

Say something very similar to:

"Now in this auspicious time and place in (state the name of your city/town that you are in here) I (state your full spiritual name or regular name if you don't have one) worship (state the name of the form of the divine that you are worshipping)"

-Invoking the divine-

Say something like: "Please dear (name of the divine) come have a seat
(motion towards the representation of the divine on your altar with
your right hand).. And may you enjoy your stay here"

-Offering of the elements to the divine-

Take your air element item and start to circle it clockwise before
your representation of the divine and say something like:

"I offer to you dear (name of the divine) this incense which represents the
element air"

Take your fire element item and start to circle it clockwise before
your representation of the divine and say something like:

"I offer to you dear (name of the divine) this lamp/candle which represents the element fire"

Take your water element item and start to circle it clockwise before
your representation of the divine and say something like:

"I offer to you dear (name of the divine) this water filled pot/cup which
represents the element water"

Take your earth element item and start to circle it clockwise before
your representation of the divine and say something like:

"I offer to you dear (name of the divine) this rice/flowers which represents the element earth"

Now bow down before your representation of the divine and then stand
back up and say something like:

"I offer to you dear (name of the divine) my prayers which represent the element spirit" and then say some mantra or prayer sacred to you three times.

Now say something like:

"Dear (name of the divine) I have offered you all these elements which are the whole of that which makes up the material universe."

-Optional Arati (purification of the aura)-

If you know the verses you can chant the appropriate arati bhajan for
your representation of the divine while doing this, otherwise it's not
necessary.

Light the camphor and circle it in front of your representation of the divine first in a clockwise direction and then in a counter-clockwise direction.

Now circle the burning camphor around yourself (being careful not to burn yourself) first in a counter-clockwise direction (clockwise to someone facing you) and then
in a clockwise direction.

-Closing of the ritual-

Say something like:

"Please dear (name of the divine) forgive me for any errors or mistakes that I may make and offer me your guidance in my life journey."

Now chant: