Is it safe to use PBEWithMD5AndDES? I'm encrypting some of my (not so much important) files with PBEWithMD5AndDES. Is it a strong method or it can be de-crypt easily without knowing my selected password? 

I'm new to crypto, thanks in advance.
Yes, it can be decrypted easily because it will use DES (CBC) mode of operation. DES only has an effective key size of 56 bits. So the key and the can be brute forced regardless of the (PBKDF1) key derivation.

MD5, while considered broken by itself, is less of an issue when it is used within PBKDF1 - as long as the password contains enough entropy of course.

If possible you should upgrade to Password Based Encryption (PBE) using PBKDF2 and AES. Beware that PBE usually uses CBC mode encryption, so it is not suitable for transport protocols.