my two bit...
Usualy Saligramam is part of the panchyuta devtatas and usually is handed over or comes down from ones lineage from grand parents, parents etc.
Second possibility is that a guru or elder or a friend has gifted the same.
Third possibility is that one has purchased saligramam oneself.
If as a parent/gurus order or instruction was to do nitya puja or when you bought it yourself then your own sankalpa was to do nitya puja then you have to do puja everyday.
In all other cases puja should be done as frequently as possible. Sunday, holidays, ekadasi, purnima days etc.
If you know purusha, narayana, vishnu suktams or vishnu sahsranamam recite them while you doing abhsihekam.
You can buy pooja vidanam book from giri trading.
Puja starts with suklamabharataram+pranayamam, sankalpalama, simple kalas pujai, sanka pujai and starts with Abshishekam of water, milk, curd, cocunut water, panchamritam, sandle wood powder etc and then throughly clean with water and then dry the idol.
Apply chandanam, kumkumam.
Do vishnu or krishnas archani with tulsi leaves.
Doopam, deepam, naivedyam (on special days payasam, sojji or sheera), kalpura arti, mantra puspam, shama prartana, namaskaram .
blessings when done atmaratam with complete surrender, faith and belief is immense.
best wishes