Myself & 2 brothers have inherited a half share in my late Mother's house. The other half is owned by a friend. How do we go about adding our names to the title deeds please?

Th executor your mother's estate should contact the County Recorder of Deeds to find out what forms and fees are involved. I assume that the joint ownership that existed between your morther and the friend was Joint Tenants in Common, not Joint Tenants with Rights of Survivorship, and that there was no mortgage, correct?