To resize billboard advert

Hi, looking for someone who can resize our billboard advert so it's the following dimensions:

Left to right 900mm
Top to bottom 600mm

The above dimensions are for a landscape poster so the design must look appropriate for landscape. We'll send you the open files.

We want you if you've had experience in this and please send across work that you've done previously that's related to this.

Look forward to hear from you.