Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Thee all around Garen
If your looking for a guide on how to jungle/farm/play as a team then i suggest either youtube or just practice. This is a pretty beefy Garen build so your an off tank if you build this way. depending on the opposite teams composition get either force of nature or thornmail but not both. If the team is quite balanced then go for a guardians angel instead.
Tips would be use the brush to your advantage. Ghost + decisive strike can get your moving quite fast so use that to flee or to close the gap.