With your InDesign file open, select the element (e.g. a box) which is over ink weight.
For example, if that box has the colour of 90C 80M 70Y 60K, it’s total ink weight is 300% (90+80+70+60 or cyan+magenta+yellow+black).
The ink limit of the publication will be shown by clicking ‘File Report’ in the ‘Manage Ads’ tab in your Websend website.
So, if the ink limit is 230%, ensure the total colour of that box is 230% or less.
This can be done by reducing the percentages of the colour by clicking the colour swatch in InDesign/Illustrator.
Save the file, reexport it as a PDF and re-upload it on the Adsend website again.