Adding liquidity through Zapper is much easier than adding liquidity manually. To provide liquidity in liquidity pools on Uniswap or SushiSwap, one has to prepare a 50/50 provision of 2 tokens in advance, but with a Zap, one can deposit a single asset that gets split 50/50 before depositing into Zapper.
What's happening is Zapper checks which token is more in demand in the liquidity pool so that we can ensure the provision maximizes your share of the pool.
An example below would be that you're zapping into the USDC/ETH LP in SushiSwap with ETH. The Zap will swap 50% of your ETH into USDC and then deposit the 2 tokens into SushiSwap so one can become a liquidity provider earning market-making fees and potentially LP rewards.
To summarize the steps below, do the following to Zap into an LP:
1. Go to Zapper.fi/invest
2. Go to Explore Opportunities and search for a liquidity pool you'd like to enter
3. Click Add Liquidity
4. Choose a token to deposit (it may be one of the 2 pool tokens but be aware you can also Zap in with more liquid tokens not in the pool such as DAI, ETH, USDC, and USDT).
5. Specify the Transaction Settings (preferred gas price) and Slippage Tolerance, which is commonly set at 1%, 2%, or 3%, depending on how liquid the pool is.
6. Click Approve or Confirm. If it's a token other than ETH, you'll have to Approve a spending limit first to deposit that token. The second transaction is to confirm a Zap In.
For a more in depth tutorial, consider watching this longer video by DeFi Dad about how Zaps work and how to Zap into a liquidity pool!