Basic process is
1. Select a small section of your sheet.
2. Click 'Excel jeanie Html' on either the Excel jeanie tollbar or the EJH4e menu.
3. Click 'Forum Standard' on the Excel jeanie interface.
4. Move to your thread and Paste (Ctrl+v or use right-click menu). That will paste the HTML code into your post and when you 'Submit' the code will be rendered into a screen shot.
There are a few other choices on the 'Forum' tab of Excel jeanie about whether you want to show Data Validation, Conditional Formatting etc. I don't believe the other tabs on Excel jeanie are relevant to posting in a forum like this.
One word of caution though. If you are posting a section of worksheet that contains a lot of similar formulas, please use the ‘Analyse range (Forum)’ field near the top left of the Excel jeanie screen to restrict the number of formulas generated. In that field, you can use Ctrl+Click/Drag to select multiple disjoint ranges if required. There is generally no need to display multiple formulas that are basically the same, it just fills up the board.