How to add image in sales quote

I have created a custom field in sales quote of image, but while creating sales quote i am unable to add image for that. kindly let me know how to add image.

please search the forum. these have been discussed many times and necessary instructions provided.

Read the Guide:

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The guide was replaced some time ago.

Use the search function in the guides to find the updated version

There’s a search function on the guides index page.
It’s actually useful just to read through the guides index page to get an idea of the sort of things covered by the guides.

In this case this part of the guides is probably relevant

Custom Fields: Use custom fields | Add an image to a custom field