Dear......... I'm so sorry that I've not been in touch for so long, how's everything? (ask about things they were doing last). I've not been able to write because I've been so busy with............... ......... ... and I never seem to have enough time. Just because I didn't write or phone you often, doesn't mean I didn't think about you often, because I did. I'd love to see you again and catch up with you, if you have the time. I hope this letter finds you well, and I hope to hear from you soon. Yours ........................... don't forget to put all of your contact details on.

Hi, (insert name)! I'm sorry I haven't written to you lately. I've been studying hard/working hard/doing a lot of overtime recently. Why don't we meet at (insert name of place) this (insert day of week)? Your buddy, (insert your name)

Follow the prompt (the directions). You start with a salutation (Querido fulano). Then you apologize for not writing before (Discúlpame por no haberte escrito antes). Tell them what you have been doing lately (durante las últimas dos semanas, he estado muy ocupado con las clases, porque ya vamos a terminar el año. También he trabajado mucho en el jardín, etc.). Lastly, invite them to do something. With the instructions you have, you don't really need a model! Put a greeting, the body (a couple paragraphs), a closing and a valediction. If someone gives you any more of a model than that in English, they will have done the work for you!