The sidebar links are typically in index.html within a <ul class="sidebar-nav"> tag. Modify the href attributes and link text to point to your actual pages.
If you want a robust portal without a high upfront cost, consider open-source software. These are completely free to download and use: Adj Portal Starter Free Download
Warning: Because "free download" is a popular search term, many malicious sites offer fake "cracked" versions filled with malware. Always prioritize official or trusted open-source repositories. The sidebar links are typically in index
Here are the safest methods to get the Adj Portal Starter for free: Adj Portal Starter Free Download