Each of the networks has a dedicated block explorer web site associated with it. This is a useful tool for monitoring network activity.
Logging in with the Ledger Nano
Return to the block explorer landing page and click on the key button in the top right corner. You'll then be prompted to "Sign in With Ledger". You must accept this request on your ledger nano device. After completing this process, the key button will be replaced by a person icon with a link to your personal address page, which keeps track of the activity that you have performed on the test-net.
Getting Testnet Tokens from the Faucet
For networks that support it, you can obtain tokens for your account by copying the address and pasting it into the token faucet. Then, return to the main page, press the "Get Funds" button and paste your address in the pop-up. Afterwards you can return to your address page (via the person icon) and should observe that you have been allocated 1 TESTFET.
Transferring Tokens to another Address
After receiving tokens, you can send these to another address using the purple Transfer button on your address page. This will trigger a pop-up that prompts you to specify the destination address and the amount you wish to transfer. After filling in this information, you will be asked to sign the transaction using your ledger nano. The confirmation that the transaction has been broadcast gives two links that can be used to check that the transaction has been executed on the blockchain using either the transaction hash or your account page.
The transaction format includes a memo field that can be used to check the transaction information on the ledger nano display.