Install tahoe-lafs in Ubuntu 20.04 over I2P

[I2P_jgtdsf66rt]

I tried to install tahoe-lafs in Ubuntu 20.04 over I2P. I can start the client and see the web interface but
no indroducer or nodes are connected. My problem is I don't really understand how to create/import
introducer and nodes. Can I use a Grid only with create an indroducer and a node or must I find furls of nodes in the
internet? If I find nodes and indroducers in the internet, how can I be shure they are active and how I must put it in the config file?

Thank you for your help