First, it is always a good idea to fill out your profile so other forum members can get a better idea of who you and where you're at before they interact with you. It's kind of how you introduce yourself to the forum.
Numbers above the music can:
- indicate the string which the note, or sequence of notes, are suggested to be played on
- provide a count of the measures
- suggest a fingering, but I'm not sure if this occurs much in "real" scores. Maybe it is more common in method books and instructional aids
As far as the symbols are concerned, there is a ^ for an up bow (starting at the tip and going to the frog) and a [ rotated 90 degrees clockwise for a down bow. These could be the symbols that you are refering to, maybe. There are others, such as ~ for a trill.
The bottom line is, you should find an instructor. If you try this on your own you can injur your hand/wrist. If you fill out your profile others might be able to suggest teachers in your area.
Welcome aboard! Double bass is not an easy instrument, if such a thing exists, but it is a very satisfying instrument to play. Here on TB there are players that are beginning, some absolute world class players who contribute, and everything in between. There is also the Ask a Pro section with Patrick Neher, Lynn Seaton and David Ruby - three phenomenal bassists. They are generous enough to answer questions that are posed to them.
Best of luck on your DB journey.
Jim