If you are using an old version of Mosaic, such as MacMosaic 1.x, there is a search field in the upper right where you can type something, and a button to press to do the search. If you're using lynx, use 's' to search. If you're using anything else, you're on your own. The search word must match the name of the cell, its lineage name, or the description.
Partial matches work.
You can use a Perl regular expression if you need to do something fancier. Otherwise don't worry about it.