Images
Photobucket >>> May not be free now - Use these image hosting sites instead.
Create an account.
Use the folder with your name on it, or create a subfolder (recommended).
Click New Album > Save
Go to "Upload Images and Videos".
Click on Choose Files.

This will most likely bring up your "Pictures-folder" (but you can select another folder).
Double click on the file you want to upload.
Wait a few seconds, and you will see it.
Click on your picture.
On top of the picture you will see “Resize”.
The best size is 640x480.
Once the image has been uploaded, you will be presented with a choice of codes.
Each code is to be used for different purposes.

If you want to post this picture directly on the Forum, click on IMG-code (last link), then right click on that and COPY.
If you only want to post the link to the picture, click on Direct-link, then right click and COPY.
Paste into your post.
If you chose IMG, the picture will only show up AFTER you posted.
In the posting you will only see the link.
If you chose "Direct link", it will just be a link.
Imageshack
It creates thumbnails for big images, which you can embed, with a link to the original image.
In the quick reply box you will see the uploader.
Browse to the image & click host it !

You will see a something like this:

All you need to do is copy the code for adding images into a forum, highlighted in the screen shot.
Paste the code in the reply text box.
Auto-resizing the image to specific sizes
Select the resolution from the drop-down menu, check the "Resize image" box:

If you want to embed the full sized image without thumbnails
1. Use the code "Hotlink for forums".
2. Copy the "Direct-link to image", then paste between [img] [/img]-tags.
How to embed videos
YouTube videos
Use the following BB-code: Code:
[youtube ]xxxxxxx[/youtube ]
Note: remove the extra space-character between youtube and ]
Fx. with the URL youtube.com/watch?v=csFsdA5F3i8&feature=player_embedded
then copy the part between = and &: (csFsdA5F3i8) and use [youtube ]csFsdA5F3i8[/youtube ]
Vimeo videos
Code:
[vimeo ]xxxxx[/vimeo ]
Note: remove the extra space-character between vimeo and ]
Note: If you click on the icon in the top-menu:
you will only insert a link to the video,
not embed it.