To move the Timeline playhead, enter the TC value in the Canvas window - not the Viewer.
If your clip is in the Viewer, move the Timeline playhead where you want it by the method above. Hit F10 to do an Overwrite Edit or F9 for an Insert Edit.
If the clip is already in the Timeline and you just want to move it, highlight the clip and enter the amount you want it to move. For example, the clip currently sits at 0:14:30:00 and you want to move it to 0:15:00:00. Highlight the clip and then type 3000 (for 30 seconds and 00 frames). If there are no other clips in its way, it will move to where you want it. If you need to move it the other direction, enter a - before the numbers (ie: -3000)
-DH