best way to introduce to the outside

Hi,

I have a cat named Ebony who is going to be 1 in a few days, ive had since she was 8weeks old. for the last couple of weeks she has been showing a intrest in going out when the garden door is open, but ive always put her in another room in fear of her going out and her not coming back anyways i ended up buying her a lead so she could go out, and have been taking her ouside every so often. At 1st she had her tail between her legs and cowered to the floor, but now she is walkin on the lead and seems alot more relaxed. I decided to see how she went today with me taking the lead off, and her movemnets was alot more relaxed and free, she was chasing flys and laying in the grass. My concern came when she was eyeing up the ramp type rubble that leads to the neigbours garden, she looked liked she wanted to climb it but I brought her inside before she could. To sum it all up I am really worried that she wonders far from reach and i will loose her can anyone tell me what I should do from her ,she obviously prefers it without the lead, and seems comfortable enough to be wanting to go over the next garden, should I just let her? what precautions should I take? ANY info would really be usefull. thanks for reading,

Pearl