Mustang & Fords is dedicated to modifying and restomodding vintage/classic Mustangs and Fords and is a good choice if you really don't have a lot of background. Just realize that over the last few years the vast majority of their tech articles are basically infomercials for their advertisers' products. Also, typically, the articles are very shallow in their actual "tech" content. For example, in the most recent issue, there is an article they titled "Holley supertuning", but the article doesn't ever actually mention specific (or even general) tuning tips. Instead the entire article simply describes various parts of Holley carbs and
what they're supposed to do (not
how they work, mind you).
Mustang Monthly is similar except it is more geared towards restoration info rather than modification (though it is doing more of that kind of thing).
My favorite purely Mustang magazine is Hemmings Mustang magazine. It is a true enthusiasts' magazine, with good tech info, geared towards do-it-yourselfers, and has a good grassroots' feel. It does cover some late model stuff, but is still primarily about classics. It's only published every 2 months, so you've got to wait a while for the next issue. But, they don't have any advertisers at all, and therefor don't have a need to appease or push certain companies or their products. I like that a lot. Also, one of our own Stangnetter's writes for them and is always prowling this forum for good fodder for articles, so I know the content is in line with my interests.
Ultimately, I suggest visiting all of the magazines' web sites and getting a free issue mailed to you. All of the magazines offer this (usually as a way to get you to subscribe). You don't like the magazine, send back the envelope with the "no thanks" box checked. Here are the sites for the ones I mentioned:
http://www.mustangandfords.com/
http://www.mustangmonthly.com/
http://www.mustangguides.com/
Hope this helps.