How, exactly, do I place an ad on my blog?

[MrD]

Please don't tell me that trying to do affiliate marketing is premature for me at this point; I already suspect that, but I want to try anyway.

I have a fairly widely-read blog, and I need to make a little money, but I am probably the most computer-ignorant adult in the Western hemisphere. I've been accepted by several affiliate marketing programs, and have wonderful ads available, but I don't understand how to place them on my blog. The instructions, from the marketers as well as from blogspot.com, assume that one knows more computerese than I know.

Can someone please, in pure, SIMPLE, step-by-step English, tell me how to place ads on my blog? And no, I do NOT intend to overload my blog with ads.
@Jake: Thanks so much for your response. I'm not using Wordpress; I'm on blogspot.com.

[Jake]

If it's wordpress there may be a plugin that helps add banners to the side bar, I use one that rotates a different ad on each page view and also logs ad clicks, some themes have ad units build in, you might find 125x125 common. You may be able to just insert a banner image into the body of an article and assign it the affiliate url.

Very often banner ads are simply the wrong approach for an affiliate blog, while there are few options if you are renting space to an ad network, an affiliate can be more effective with a simple text link an a pre-sell article or product comparison, there can be a much higher trust in something you recommend.

The FTC does want to see a disclaimer that you may be receiving a commission for some of your recommendations.