My dreamview of an ALTAR/ALTER is:

A symbol of religioin, devotion, worship, prayer, piety, meditation, answers to prayer, descision making and sacrifice.

Seeing an Altar:

Being made aware of the fact that you need to devote some time/effort to your spirituality, that you need to "sacrifice" your priorities in order to gain Spirituality.  

Making an offering of grains or seeds:

You are "offering up" yourself, your material posessions and/or wealth, your earthly priorities in order to receive Spiritual Germination and/or Growth.

Making an animal (blood) offering:

You are sacrificing "a life" in order to absolve yourself Spiritually for something you may have done, said or thought that incurred Karmic repercussions.  The kind of animal may be indicative of the type of Karmic debt you incurred.

Making an offering of fruits and flowers:

The fruits of your labours are the payoff for hard work and perhaps even hardship.  Now you have picked the fruits and share it with the Cosmic Forces who stood behind you and gave you courage and encouragement and guidance during this period of your labour. You are blessed...

Only add to, or discuss your interpretation of this dream symbol...please