Hearthpwn

I used Mid range pally with a few secrets this season to get to legend (basically I use 2x Avenge,1x Competetive spirit and don't even run mysterious challenger)  .It fairs pretty well against the other decks out there including most aggro and control decks.

Just play as many games as possible you will eventually get there. If you keep loosing you probably are doing something wrong, new players tend to make misplays and mistakes in mulligan and when to use key-cards ( although the learning curve for secret pally is extremely low) so I advise you to watch some streamers play secret pally or read up a guide.(if you are on a loosing streak for 5+ games in a row take a break.. trust me it will help you)
Good luck