Kenny, here's what I do. I'm going to provide detailed, step-by-step instructions, in case the answers given already seem incomplete or insufficient for your needs.
I use Google drive. It's a free service, and as part of the Google accounts, it has a gargantuan amount of file space, way more than you'd ever use for maps or character portraits. Unfortunately, it's something that requires a computer; you cannot use a phone or tablet for this.
1a) Login to Google drive, or register if you have not already done so.
Link to Google Drive
1b) Within Google drive (drive.google.com), I make a subdirectory/folder for each game.
2a) Then I drag the map that I've created to that folder. By default, files on Google drive are private to you, so you'll need to change the permissions so that someone external (like a web site such as Gamer's Plane) will be able to access it.
2b) Right click on the file and select "Share" from the context menu that appears. This will open a pop-up window called "Sharing Settings."
2c) In the "Sharing Settings" pop-up window, select "Advanced." The pop-up will show a "Link to share" and a list of "Who has access." This "Who has access" will probably show "Private."
2d) Next to where it says "Private," click "Change." This will show a set of three radio buttons; select "On - Public on the Web," then click the "Save" button. Saving your change will return you to the "Sharing Settings" view in the pop-up window.
2e) Select the text of the "link to share" and copy it (command+C on a Mac, CTRL+C on a Windows PC). For example, this link to share for one of my maps is: https://drive.google.com/file/d/0B071DukoNZd1ZnlBd2dQaHN3Zk0/view?usp=sharing
2f) Click "done" to get rid of the pop-up window.
3a) Return to the window/tab that you have open on Gamer's Plane. You now have to use the link, and modify it so that it will display on GP.
3b) Paste the link to the thread post where you want it to be. Unfortunately, this link is NOT ready to display on GP; Google's link sharing is designed to only work if a user clicks on it in e-mail. For the image to display on a message board like GP, you will need to alter it from what Google has provided.
3c) Look at the link you pasted from Google drive. In the middle of the link is a large string of seemingly random characters; this is the actual file ID for your image. In my example, that's 0B071DukoNZd1ZnlBd2dQaHN3Zk0
3d) Replace everything in the link you pasted before your file's ID with this:
http://drive.google.com/uc?export=view&id=
and delete everything after your file's ID.
So, with my example, it would go from this:
https://drive.google.com/file/d/0B071DukoNZd1ZnlBd2dQaHN3Zk0/view?usp=sharing
to this:
http://drive.google.com/uc?export=view&id=0B071DukoNZd1ZnlBd2dQaHN3Zk0
3e) The last thing to do in your post is to enclose that link with the [ img ] and [ /img ] tags, as you would with any img reference.
Like this:
[ img ]http://drive.google.com/uc?export=view&id=0B071DukoNZd1ZnlBd2dQaHN3Zk0[ /img ]
(remove the spaces in the square brackets)
Note that you can also just post that finished link into the "Add Image" dialog box (and GP will provide the img tags), just as Jabes.plays.RPG suggested.
4) Add whatever text you want to appear along with the image either before or after that, and then click "Post." It will then appear like this (my example):
Last edited November 23, 2015 8:15 am