For a first quick Internet access test: If you have an existing router, connect the WAN port of your LEDE device to a LAN port of that router and confirm internet connectivity of your LEDE device with the following steps:
In the LEDE admin web GUI, go to Network → Diagnostics and Click on “ping” button
or, if using LEDE SSH command line, you can use the command ping lede-project.org
This should return “0% packet loss” if everything is allright with your Internet connection.
When using your LEDE device as a WiFi access point, remember to initially set your country code in the LEDE WiFi configuration, to properly comply with your country's WiFi legal regulation!, e.g. see here for a first basic WiFi setup.
Consult the User Guide for more advanced configuration.
Install custom software packages that you might be interested in.
Troubleshooting your first steps with the new LEDE device:
If you have flashed a development/snapshot firmware of LEDE, you first need to manually enable the admin web GUI: development installation guide. Or verify the result on snapshot builds by SSH-connecting to your LEDE device IP 192.168.1.1
You can consult the troubleshooting section of the User Guide, if you think that resetting LEDE's settings might help.