Building a cinder block wall need some help?

You can use the plank as a footer as suggested and use a sand and lime mixture instead of a cement mortar it will stiffen up just as an ordinary mortar would but will come apart easily and should you need to knock it up again just add water could you not build it where you intend to show it off as transporting it will be tricky just knock up the mixture 4 sand 1 lime and add water you could end up hurting yourself or someone else should it fall down,good luck anyway.