[AccessD] OT: Excel - Merge several cells

I need to "merge" several cells to create one big cell.  I have seen this in
spreadsheets but have no idea how to do it myself.

Any clue?

For example, a1,b1,c1 becomes one big cell, but a2,b2,c3 and all the cells
below them remain as they were.  I need to put text in a "header cell".

TIA

John W. Colby
Colby Consulting
www.ColbyConsulting.com