It is bidirectional by default. In fact LND does not even allow for single-directional channels.
What you're experiencing though, is the drawback of having created a single-funded channel. That means, that all of the funds in your newly created channel are sitting on your side, which means that for now, you can only send money but not receive any money. Or in other words, you don't have any inbound capacity on that very channel. As soon as you do have both inbound and outbound capacity, you will be able to both send and receive money over that channel.
Note: For now the Lightning implementations do not allow for mutually funded channels, but this feature is in the works and soon to come.
So.. what are your possibilities now to circumvent this problem and get inbound capacity? Here are some options:
- Wait until other nodes open channels to your node
- Push money to the other side of the channel by buying something
- Send money over Lightning to zigzag.io and receive it back on-chain.
Once you have inbound capacity and you are routing payments, your channels will get rebalanced in the process and you will hopefully get inbound capacity on all of your channels over time.