Hey Lois you can put as many affiliate ads as you'd like, but I'm going to suggest to refrain from ads until you start building good traffic to your site. If you have good traffic then go for it.

The reason why I suggest refraining from ads, is that it can distract your readers, it makes your site run a little on the slow side, plus ads are a testing thing. Too many ads can turn off a reader or confuse them.

Some ads may work on your site, while other wont. If you don't have traffic it's hard to test. These ads can just sit there and not do anything for your business. You want ads that are going to help build your business and revenue. I hope I was helpful if you have any questions feel free to ask. :)

I also want to state that you can do whatever you feel is appropriate, this is just my suggestion. :) Evelyn

you can put as many affiliate ads as you want on your website but im guessing you downloaded the adsence plugin. They only allow you to put 3 google adsence ads with that specific plugin