Hi, I'm not a native speaker but I think I can help you.

Escrito - this is the past participle of the verb "escribir". Past participles can be used as adjectives in Spanish, so escrita is just the feminine version of the past participle. I can't think of a decent example with "escrita" so I'll use the verb "abrir" instead. The past participle of "abrir" is abierto. So "la puerta está abierta" - you have to change abierto to abierta since the noun it is modifying is feminine.

I think you meant to write "ecritura" not "escrituro" I've never heard of escrituro. This is the noun form of the verb "escribir". Like in English you can say "I'm trying to improve my writing". En español sería "Intento mejorar mi escritura".

Escribiendo - this is the present participle. It's used to with the auxilary verb "estar" to describe things that are actually happening in the moment. It can also be used as a noun under certain circumstances I think but I'm not entirely sure about when. E.g. Somebody asks you "what are you doing?" you can reply "estoy escribiendo" I'm writing, or "estoy leyendo" I'm reading. 

Hello Brendan: maybe I could help you.

Escrito: is used as adjective as well as past participle. As Adjective you can use the masculine "escrito" and the femenine "escrita" >>> "mi agenda esta escrita" (my agenda is written) / "En esta pizarra esta escrito el menú" (in this board the menu is written)

As past participle > "Aqui se han escrito las primeras leyes" (the first laws was written here) and this form is used with the auxiliary "he/ha/han/has" ("haber" verb)

"Escritura" is a noun, and it means writing or script >>> "Las Sagradas Escrituras" (the holy scriptures)

Escribiendo is the gerund of "escribir", (I mean the -ing form) Escribir > Escribiendo "He estado escribiendo una novela" (I was writing a novel)

Escrito is just the past participle which appears in the compound tenses formed with "haber".

Like "he escrito" I have written. But past participles can also be used as adjectives in Spanish, so they have four forms to account for number and gender like most other adjectives. You could potentially see any of the follwing forms when the past participle escrito is functioning as an adjective: escrito, escritos, escrita, escritas. 

Por ejemplo: Las historias son muy bien escritas. - The stories are very well written.

It's like any other adjective let's take "caro" (expensive) as another example so you can see how they both work in the same way. Caro has four forms: caro, caros, cara, caras. 

If you wanted to say "That car is quite expensive" you could say "Aquel coche es bastante caro."

And if you wanted to say "That table is quite expensive" you could say "Esa mesa es bastante cara." You just add an "s" onto the end to make it plural. 

fantastic, we are making progress ;) sorry I accidentally wrote "improve" but I meant "practice" but thankyou for confirming the examples were correct even though I mistyped the english.

now the last mystery is the use of escrito/escrita

thanks spangola, you have definately already helped to clear some of the confusion up

re escritura I guess a sentence could technically be "I am writing becuase I need to improve my writing"

which would me estoy escribiendo porque para practicar mi escritura"? would that be correct?

@ bold - nope. It would be "Estoy escribiendo porque necesito mejorar mi escritura." (I'm writing because I need to improve my writing)

And also escritura would be like "I need to improve my writing (escritura) skills becuase they are really awful" for example?

The above is correct.