Blogs are the easiest type of porn site to make and without a doubt the best for a beginner trying to get a feel for everything and they are a lot of fun too if you like to write. Your content would be coming from affiliate pages (like signup at bangbros, naughty america, etc), log in to the affiliate page, pick free hosted galleries/content with MILFs, and then (for example) preview a particular gallery, post a picture that links to the full gallery with your affiliate id in the URL, and then write a few hundred words about it using key words like 'milf, cougar, big tits, fake tits, etc etc' basically you're using common words/phrases that people would search for on google, and then keep on updating it on a regular basis, the more posts you have, the more unique content you have, the more likely you will get traffic when somebody searches for something.
From there comes all the strategic SEO stuff to move your site up the search rankings and I know next to nothing there (ugh) but maybe somebody else will chime in on that.
Anyway, Here is a good blog example:
http://hotmilfs.kinkyblog.net/
That's not my blog or anything, just found it on Google... I think that one exemplifies what I am talking about but then again I AM at work and I can't look too hard and risk someone seeing me look at porn ... but hopefully that gives you a bit of an idea.