When posting a new topic or reply, click on a the attachments link, them choose file.
Yes, this is how to upload images here. Max 10 per post and limited to so many megabytes per image and in total.
Embedding the photos into the text area is hit and miss.
Also correct, but there are ways to do it with not to much effort. Simply upload your images when making the post and then use the "modify" button to edit your post, but do it in a new tab. (right click on the button and select open in new tab)
Then use the embed image button to place your image in the text where you want it. (Button next to the insert hyperlink button in the formatting section of the editor) Go to the other tab and copy the link of the image you want in the created image space and paste it between the [ img ] [ /img ] markers. (spaces added here to make them visible as text)
Save your edited message and it is done. When done quick enough you won't get the "Last edited" message.
Personally I use https://postimages.org/ if I have many photos. Upland your photos and then copy the forum code and paste it into the editor.
This has been advised against many times because it can break posts when the used image platform goes bust or the images are lost otherwise. Your post looks silly then without the photos.
Also consider to resize your images to not take up to much screen space and make sure they are not to big in data size. A lot of forum users are still on slower connections and are hindered by the slow loading images.