I'm using RHEL. I want to insert an image in
gedit, but I'm not able to do so. Also I'm unable to install LibreOffice because they are asking for a subscription. Any alternate to
gedit or can we insert image in
gedit is strictly a text editor, and does not provide a method for inserting images or embedding images within its files.
I think you're getting confused on the subscription details. The subscription is probably because you're using RHEL, LibreOffice is a free product, you can download the RPMs directly from the project's website and install them manually.
See this page for the RPMs.
Downloading & Installation
Take a look at the extensive documentation that already exists on the LibreOffice website. It'll take you through the various installation steps.