Door Repair - 2x6 bolted together
Suppose I were to ask a master chef how difficult it would be to assemble some dish of theirs? Of course, for the expert it is trivial. But for me, who has no serious knowledge of fine cooking, it might be quite a bit more work. What in the name of god and little green apples is a roux anyway? For some, dicing up an onion is done in a flash, a matter of seconds. For others, it may well involve a spot or two of their own blood spilled. The same may be true of any task. Much depends on your level of skill, upon your willingness to learn, upon a variety of factors.

In the case of a door, how is the door assembled? Is it joined with glue, that must be taken apart and then later reassembled? Are bolts truly the only method of attachment? What species is the wood? Will you find a new piece of wood that is an adequate replacement? Do you have the tools to cut that large piece of wood accurately to the proper size? Is there any rot in the wood that must be repaired before it goes back together?

You might try taking the door apart, then if you can remove the damaged (split?) section, take that piece to a dealer in hardwoods. Don't just go to the local Home Depot and expect to find a replacement. It won't be a match in terms of species anyway, and the wood you will find there is of poor quality, expensive for what you get, and may well warp on you anyway. All wood is not the same. Your local hardwood dealer will be able to find a match for your board, and for a very reasonable fee, even cut it to size for you.

Finally, you must know that new, freshly milled wood will often have a very different color and patina than old weathered wood. For example, fresh walnut or cherry both look VERY different from aged wood of the same species. While it is not always difficult to achieve a match, this too can take some expertise. Practice on a scrap piece before you go near the final work.

In the end, yes, you can probably do this task. It will take you a longer time to get it right than it would if done by an expert, but with persistence, a willingness to learn, and a little guidance you can get there. And once you are done, you shall be satisfied to say it was you who did it.