How to create Homebrew Sword?

Hello,

I have an idea of creating a Homebrew Sword that is +10 to hit with 2d8 + 5 damage. I experimented with a few of the modifiers but still didn't seem to affect the "to hit" and "damage" amounts shown on the character sheet.

Any suggestion or instruction?

Can't have bonus to hit for that item. You can make a bonus that applies to general attacks (like all melee attacks, all unarmed attacks, all spell attacks, etc). 

The bonus to hit and damage should be the same, then you can use Modifier Bonus, Subtype Magic and Fixed Value is the bonus you want to add : this will add the bonus to both to hit and damage (this is how +1/+2/+3 items are done).