I just need advice on what cards to take or add to my deck to make it better. Also, if you could, please help me with lands.
Deck: https://deckbox.org/sets/812966

At the most rudimentary level, you need to have dual lands if you are going to play 3 colors. Playing just basics is just asking to get mana screwed during game play IMHO.
Even having the uncommon dual lands is better than nothing, plus you do have the benefit of a little life gain. Obviously, having lands likellanowar wastes and caves of koilos from m15 would be beneficial because it does not enter the battlefield tapped. since it looks like you need to speed on your side, these might be the best bet even though they do some damage to you. I like temples for scry ability, but I don't think they would work for what you are trying to do in your deck.
Looks like a bit of a sliver flavor you are going for with the outlast.. should be a fun deck to try :)