You can add peers manually. Just open ~/.bitmark/bitmark.conf (-linux/mac path) and append at the end of file:
addnode=175.100.3.95
addnode=93.107.125.126
addnode=204.68.122.11
addnode=42.232.206.100
addnode=139.162.232.242
More peers can be found in bitmark explorer:
http://btm.cryptocloudhosting.org/networkAt this moment you can't withdraw BTM from Poloniex, withdrawals are suspended for some time on Poloniex, but you can buy BTM on tradesathosi(
https://tradesatoshi.com/Exchange?market=BTM_BTC), for the fraction of Poloniex price.
Also begin of March Bitmark will be added to Cryptopia, so you will be able to trade there as well.
You can add peers manually from the wallet. Help>Debug Window>Console