John.. welcome to WGT ... glad to have you.
Now, the credits are actually 50 for making Amatuer and 100 for making Pro.. your earnings should say $1.50 but someone borked the decimal place in the last update. If you will look under 'account' over there <--------- you will see your actual credits.
These credits can be used to buy more and better equipment... but I will tell you that 150 will not buy a lot of stuff. A full set of new clubs will probably cost in the neighborhood of $20 to $25... that's 2000 - 2500 credits. Golf balls can go for as little as 14 credits to 50 credits for a sleeve of 3.
Hope this helps.. if you need anything else, ask away.. also, the search feature for the forums is a great help as well.