magic the gathering should i?

to answer your question, we first need to know why you keep losing with your mono black deck.

Q1: is the build ok (ie enough land, enough win condition)?

Q2: assuming yes for Q1, then is the deck design for a specific meta game? ie, did you design it based on the most popular decks in your local stores during the past 4 weeks of fnm? if yes, then maybe the meta game has changed and you need to update your deck as the meta game evolves.

Q3: if the build is right for the meta game or even casual among friends, do you know how to pilot the deck? you can have the most powerful deck of mtg history but if you don't know how to use it properly, you still won't win game.

Q4: how you usually lose with mono black? if you lost due to decking or poison counters, high life is not going to help you.

there're ways for black to gain lifes, you may not need white. it is hard to tell without knowing your deck. and it is wrong to give any advise when there's no sufficient info.

Two black cards you should exploit if you are going to build a Black/White life gain:

Sanguine Bond- 3BB

Enchantment

Whenever you gain life, target opponent loses that much life.

Dark Tutelage- 2B

Enchantment

At the beginning of your upkeep, reveal the top card of your library and put it into your hand. You lose life equal to it's converted mana cost.

i doubt it. the two decks are enemy colors, which mean the operate on different principles. add more lands or awesome spells to the black. or maybe life drain like corrupt and blood tithe.