If both parties have made a contract on the sales commission... will the contract take place/ be admitted?

Do I need to get a lawyer to have the contract structured? Do I need a witness and who can be the witness?

I work on commission, the cmpany merely has about a one page document, it shows what commission I will make on what products, sold at specific profit levels. For example I could not make full comssion on a idea being sold at near cost on sale.

I sign it, they sign it, I get a copy they get a copy, that is all you have to do.
What type of business, what is being sold, will there be on set commission, will there be a draw against commissions, just write it all down, and have both parties sign it.

Thanks!