Depends on what exactly is stopping you NOW.
If it's the "workflow" you are requesting.
Gaea: Create your terrain. Then you export your terrain as a Tiff 32 bit heightmap, and your colormap as an 8bit or 16bit png.
Vue: Add a "heightmap terrain" in vue. Not exactly familiar with current lingo, but you add your gaea heightmap using terrain editor. Once you set detail level and import your terrain, exit the editor. Next go to material editor, switch terrain material to pbr. Add your gaea colormap in the "color" tab.
For specific tutorials, look for "importing a terrain heightmap in vue". For the gaea side, this one should do: