The process to add an SP's or IdP's metadata to eduGAIN varies from federation to federation. Therefore, it is recommended to have a look at your local federation's instructions. Generally, the necessary steps are however:
In some federations, metadata has not to be generated manually but by filling in some web forms that then generate the metadata automatically based on the entered values.
If you have to provide metadata yourself for your entity, have a look at the examples and template metadata files below. They can serve as a starting point that makes the generation a bit easier.
Most common SAML implementations (Shibboleth, SimpleSAML PHP) also generate some basic metadata automatically.
The metadata generated by these SAML implementations only includes the technical values of metadata. It does not contain any organizational values and it also does for example not contain name, description or which attributes are requested. This information has to be added manually.
This step also may not be necessary in case your local federation uses a federation registry that generates and publishes the metadata in eduGAIN for you.
Finally, contact your Federation and communicate the intention to join to eduGAIN: eduGAIN members In some federations, it is sufficient to send an email to the federation helpdesk and ask them to publish the metadata for eduGAIN. In other federations, the federation registry allows an administrator to tick a checkbox to achieve the same.