I have to file a 8949 document with my tax return and was wondering if that meant that I just had to mail my Robinhood 1099B form that they generate for me?
No. The data about sales/dispositions shown on the 1099-B (or all 1099-B's combined if you deal with more than one broker) goes on your 8949(s) (there may be more than one if you have different categories such as shortterm/longterm and covered/uncovered), and the 8949(s) and Schedule D are attached to your paper return (see the 'sequence number' in the upper right corner) or included in your e-file return. You don't file the 1099-B unless you were subject to backup withholding; in that case if you paper-file you should attach any kind of 1099 that shows withholding.
This is covered by the last step in the 1040 instructions "Assemble Your Return" -- except that these instructions only handle the forms that are used for normal domestic withholding: wages (and replacements), pensions and retirement plans (optionally), and gambling (with some exceptions), plus one rare case, undistributed fund gains (2439). There are several 1099-series forms that can include backup withholding, which is imposed if you (1) don't give a payer your SSN, or give a wrong SSN (only detected after about a year), or don't 'sign' the W-9; or (2) fail to report taxable non-wage income (including stock gains, and dividends) persistently even after being reminded (or audited).