Hey there! Welcome to Magic and the forum boards!
First off, autocarding is a must!
Tangle mantis becomes
tangle mantis 
by bracketing the card name by using the following:
[c*]cardname[/c*] but remove the *
You have a good amount of lands for a startin point, so that's good!
I see you have basically a green beatdown deck-totally a great place to start, from beginners to experts.
For a good start, having playsets of key cards is important, it helps your consistency (your % chance of drawing said card)
Watch your mana curve-if you have too many high cost spells, you will be slow and top heavy, and you won't win much.
If we can get some steering on how you want this to play out, it will be easier to give advice (you want a quick, fast deck with cheap creatures, or perhaps ramp up into the big beefy beaters green has in droves!)
-oh! Ramp, If you don't know, is using spells like
rampant growth 
and creatures like
llanowar elves 
to develop mana quickly in order to cast big cards much sooner than merely dropping a land every turn.
Hope this helps a bit! Let us know what you want to do and we will get crackin!
One last thing, I assume this is built from cards you have. I encourage you to explore the Gatherer (a website that has every magic card ever printed) for cards that help your theme, whatever that may be, and build a deck list that you envision to be the best fit for you. Don't just limit it to cards you own. By building your perfect deck, it gives you something to work for, and an idea of what cards to collect (cuz lets face it, this is a hobby that does require at least a minor cash output!)
Cheers!
21)
