Welcome,
you need a program that will work with animations.
A simple one to use, which I got with PaintShop Pro is
Animation Shop 2,,,
Both by Jasc software.
You can also get FireWorks from MacroMedia. .
But thats a heck of a lot harder to learn, but far better. .
Kinda like a Dodge Gasser Vs a Dodge Cummins truck...
You can buy PainShop Pro with the Animation shop for about 70 bucks... FireWorks is about 200 - 400 , some where in that range, dont remember.
I used Animation Shop 2 to fix yours... took a minute.
Just resized it and re-saved it...
A hint, For sure you can download a Trial version of Fireworks, but you cant save anything as I remember... since it's and industry standard... if you hunt through the crack sites. . you can find either a crack or registration serial number...
It's hard to use, so if you looking for something easier... and dont mind paying some dollars pick up the Jasc suite... Paintshop pro has gotten to be a decent , but not as powerfull , but easier to use, PhotoShop knock off. I use the full blown version of Photoshop... but for quick stuff I do use Paintshop Pro...
The Jasc programs are also MUCH less demanding on your computer's resources.