Need help to create a proposal form in excel

I am a moderate user of Excel, I am totally self taught in Excel. I can create spreadsheets with formulas and other basic tasks. My boss would like to create Customer Proposals in an Excel spread sheet format. I need different size cells at various places on the form? He also wants a place that looks like a invoice in the center to the form. Would like step by step directions to do this. I have been 'playing around' on how to do this for 2 days and need help. I went to You Tube but did not find a tutorial that could help me. If some knows of a You Tube video a link would be appreciated. Thank you in advance. Monica