Somewhere I saw directions on how to use dollar store solar lites

Here is one that was posted recently on hometalk, it may be the one you are looking for:

http://www.hometalk.com/diy/outdoor/lights/diy-solar-deck-lighting-30559003?expand_all_questions=1

Here's some ideas on using solar lights from our hometalk members. Some are on a railing and some are not, but they are ideas that you might be able to adapt.

Click here: http://www.hometalk.com/search/posts?filter=solar%20lights%20on%20railing

Good luck!

Do you already have a railing? Or do we need to build that first?

Not all dollar stores are equal. Do the solar lights at your dollar store have flat or round bases?

If round, wire loops screwed into the rail. If flat you can screw directly into the rail through the base. If you don’t want to put holes in the railing you could use some kind of tape inside out covered with something decorative. Or two layers of tape with the sticky sides facing and the solar light stem sandwiched between. Just make sure the first layer is tight before you add the solar light and the decorative (Washi?) tape.

Instead of using the poles they come with to place them in the ground, glue the top on the top of the post.

We did this, but I don't know if it's what you're looking for. We drilled 1/2" holes in the tops of our posts on the deck railing and just shoved the lights in. we didn't silicone so we can take them out for the winter but if you're planning to leave them use a little solicone to hold them in. Easy peezy simple!