Just do what you're interested in. If you think, "damn I gotta learn PHP" then go for it. I'm sure there are other reasons leading to why you want to get into that, (maybe you saw some cool script, or you were inspired by another site that might have used php to generate content w/e) but I've always found that if you follow whatever you're interested in, you'll always hit gold.

If you felt good about seeing how code breathed life into your designs than your gonna how programming is gonna add to it. Just get the ball rolling by doing what you want--that momentum will keep you on track and push you to learn even more things you never even thought of.

Trust me it's worked for me. =)