To begin a treble crochet(tr), yarn over(y/o) twice and insert hook into the next stitch:
Y/o, draw through stitch. You now have 4 loops on your hook. Y/o and draw through 2 loops:
Y/o again and draw through 2 loops:
Y/o and draw through 2 loops a third time to complete the tr:
This is what it looks like when you complete the row:
Crochetably 