If you have been making scarfs, you probably used short needles (about 8" long). You can buy circular needles, as suggested by Marriah, or longer straight needles (14" long, or so). Believe it or not, you can stuff a lot of stitches on a straight needle! Then just cast on the number of stitches that the pattern calls for and go until it's long enough.
Pick a simple pattern, and good luck!