This should get you started:
[youtube]wzOnoN9Iv-w[/youtube]

Here are some more detailed instructions:

Step 1: Can I decorate this brick?

Go to the part manager and find your desired part. If it has a "2" in the top left corner of the image you can deocrate it. Copy the part number. If you can't find your part or it doesn't have a "2" in the corner then you are done until the part gets updated.

Step 2: Download a UV map

Switch to the Parts tab, click on Custom and enter your part number in the Configuration Name window. Click the search icon and your part should pop up. Select Decorated and you will be given a drop-down of UV maps to use. These are a visual map that show what parts of your image will go on what parts of the Lego piece. Take a look through the UV maps and use the Textures preview window see which UV map will work best for you. Then download it to use as a template.

Step 3: Create your image
In a nutshell, make an image that will fit within the bounds of your chosen UV map. Your image should have a transparent background where you want to have the plastic showing through the design. If you want metallic ink or want to use a sticker (vs a print) then you will have to supply a Data image as well. Here are the rules for this: https://www.mecabricks.com/en/forum/topic/1582

Step 4: Create your custom decorated part

Go back to the parts tab, click on Custom and enter your data. Here is a breakdown of what is there:
References
Enter a Reference name for your part. This is what will show up under your part icon in the workshop parts bin. It will need to be unique within your decorations in Mecabricks. The app will not let you reuse a Reference name.
Names
This is the display name of your part. It does not need to be unique and Mechabricks will not throw an error if you double up on names.
Configuration
This is the part number that you copied from before.
Materials
Click on the dot to choose a color.
Decoration
Choose Decorated and then select the UV map number that you used to build your image.
Click the + on the Colour line to upload your image file. If it show up looking all weird in the 3D view, check to make sure that you used the correct UV map. If you made a Data file, upload it too.
Storage
Choose a storage location.
Create
Hit the Create Button

Step 5: Render an Icon

After you create your part, you will be given the option to Render an Icon in the upper right hand portion of the page. Doing this will make it easier to find it in the workshop parts bin.

That's it, you are done. Your part will be available immediately in the workshop under custom parts.

I hope this helps. Cheers!

Thanks!!!!!!

hola como descargo un mapa UV.

@Meca2609 -

Step 2: Download a UV map