not that easy for someone who has never done this type of project before. Although it can be done, its very difficult at best and really requires several hands more then you already own to do this type of project.

Most steps are not simply poured into place. In most cases a foundation is poured into place and then block is set to design the steps required. Once that is done, then cement is placed in each section or a stone slab is placed for each tread. Once done then the block is plastered with mortar to finish the look.

A single pour step is as KMS said a bit on the heavy side and can be quite difficult to do.

I understand the need to change the steps out as wood steps do have a tendency to look pretty bad, but there are many other optional products that will would work great and are more, much more, DIY friendly.