Action Details
Requirements and how-to articles for Twitter's action:

paid action
A direct message card features either an image or a video to encourage the user to send a message (not currently available for self-serve advertisers.)

You need this to get it done:

Tweet Text
Text to accompany the image/video card (maximum of 256 characters as 24 characters are used for the card.)
File format: .jpg/.png (non-animated .gif files are also supported)
Maximum file size: 3MB
Aspect ratio: 1.91:1
Minimum image width: 800 pixels
File format: .mp4/.mov
Aspect ratio: 16:9
Maximum video length: 2 minutes and 20 seconds (however some advertisers are eligible to request an increase of up to 10 minutes)
Maximum file size: 1GB
Video codec: h.264 (high profile)
Audio codec: AAC-LC
Frame rate: 30fps (frames per second)
Minimum bitrate: 5,000Kbps
Call to Action Text
The text to be featured on the call-to-action button (maximum of 24 characters, emoji is supported)
Requirements missing or found errors? Report

How-To Articles
A list of useful links for you:

Twitter Business - Advertiser creative specifications
Official information on creative specs for ads.
Link missing here or found errors? Improve How-Tos