deploy contracts:

MainChain

Lib_AddressManager (./contracts/libraries/resolver/Lib_AddressManager.sol)
MainGate (./contracts/MainChain/MainBridge/MainGate.sol)
MainBridge (./contracts/MainChain/MainBridge/MainBridge.sol)
MainNFTCollection (./contracts/MainChain/Tokens/MainNFTCollection.sol)
CanonicalTransactionChain (./contracts/MainChain/MainBridge/CanonicalTransactionChain.sol)
Transactor  (./libraries//universal/Transactor.sol)

At SideChain , we will deploy it like MainChain

Initiate

Next, initiate some contracts:

MainBridge (main)
MainGate (main)
SideBridge (side)
SideGate (side)

Set address

Then set address contractss at Lib_AddressManager

Ctrl + Shift + F and type resolve to seach some address what we need store them

main: set it on MainChain side: set it on SideChain

setAddress

MainBridge (main)
CanonicalTransactionChain (main)
SideBridge (side)
CanonicalTransactionChain (side)

setGate

sideGate (main)
mainGate (side)

setTransactor

MainTransactor (main)
SideTransactor (main)
MainTransactor (side)
SideTransactor (side)

Deposit

Before deposit NFTCollection, please setApprovalForAll NFTCollection what you want to deposit.

Catch event TransactorEvent and sign parameters (sender, target, data, messageNonce) with deadline. Send signature for user, then save these parameters with signature to database. Please check contract Transactor to know detail

When user want claim NFT, they will call function claimNFTCollection, we will check signature user sent, if valid, address target will call data. It will call function relayMessage in SideGate and then call function finalizeDeposit in SideBridge. User will receive their NFT depoisited.

Withdraw

It's similar to Deposit