Can I open long and short positions at the same time?

You can’t open long and short positions on the same market at exactly the same time with a single click. You can however open two separate trades in the same market in the opposite direction. 

CFDs are complex instruments and come with a high risk of losing money rapidly due to leverage. 79% of retail investor accounts lose money when trading CFDs with this provider.
You should consider whether you understand how CFDs work, and whether you can afford to take the high risk of losing your money.
CFDs are complex instruments and come with a high risk of losing money rapidly due to leverage.