Okay, so first of all, you should require people to have to comment to vote if you really want to learn stuff in order to improve. If you really don't care about learning from people or getting upvotes, then that's your decision.

Anyways, your coding is fine, but it's the content that's rough. You only talk about 2 masteries, but that would make your mastery section fall under the category of incomplete. You need to talk about all of your masteries, even if it's something as short as "It gives you more damage" (but try not to have all of them that short).

Secondly, you're missing some sections. Runes, summoner spells, lane phase, and conclusion (counters and lane partners is also an optional section to add).

Try not to swear much, if at all in your guide. This just makes the reader more bored, not hyped up. Check for spelling and grammar errors as well. In terms of coding, type [icon=insert desired item/ability] instead of cropping a picture. This will get you for example, to increase the icon size, type [icon=alpha strike size x]. x being whichever size you choose.

And to close, if you have more then one build, talk about all of them. Because just seeing an AP build for Master Yi and not knowing why you decided those items will usually result in a downvote. Build 2 pretty much mirrors your first build. And be sure to add defensive items, you're not always fed!

For more information, see the official Guide Making Help and Tutorials thread.