Hi there,

the F- chord is one of the toughest to master. I've been at it for three years and still sometimes I get a muffled sound out of it. I wouldn't worry about how it sounds for now. You could always leave out the low e string first fret if that's what is causing the problem. As you progress in lessons you'll discover other variations or "voicings" of the chord that might actually be easier but for now I'd recommend just keep plugging away and it will work itself out in time. How much time theres really is no definitive answer I could give you. Hang in there buddy it's a marathon not a race.

Moe