To add custom indicators to Exness MT4, first, save the indicator file (.mq4 or .ex4) on your computer. Then, open MT4 and click on "File" in the top menu, followed by "Open Data Folder." Navigate to the "MQL4" folder, then "Indicators," and paste your file here. Restart MT4, and the new indicator should appear in the "Navigator" panel under "Indicators."