Move your cursor to the top right corner and click on the Share Charm to share the gif over email or to any other app that supports sharing.
(c) copyright 2008, Blender Foundation / www.bigbuckbunny.org
You should always try to keep the animation interval as small as possible. If that is not sufficient you could try these options.
Option #1 : You could reduce the portion of the Video being Captured
Option #2 : You could choose to animate only a portion of the Video by drawing a green rectangle around the region of interest.
Option #3 : You could scale down the image using Scale Factor Slider
Tumblr seems to have a limit of 1MB for Gifs. Check the "How do I reduce the size of my Gifs?" FAQ to bring the size under 1 MB.
The Captured Gif files are stored under C:\Users\#Your_User_Id#\Pictures \VidGiffy\#Video_File_Name#\ Frame_x_x_x_x.gif
You can copy paste the folder name into the Search Charm and Press Enter Twice to open the folder. Move your cursor to the right top corner to reveal the Search charm